Inclination indicating device for oil wells



2 Sl'xeets--Sheet l Jan. 22, 1935. T, L, LYNCH ET AL INCLINATIONINDICATING DEVICE FOR OIL WELLS Filed July 7, 1930 Jan. 22, 1935. T. L.lI YNCH ET AL INCLINATIONi INDICATING DEVICE FOR OIL WELLS FiledJ'uly'fz; 195o -2 sheets-sheet 2 #T7-oever.

Patented Jan. 22, 1935 UNITED STATES mcuNA'rroN INDICATING DEVICE For.on. WELLS Theodore L. Lynch,

Billing, Long Beach Alhambra, Calif., Los Angeles, Calif.

Huntington Park, .Harry L. and Howard A. Redfield, assignors to Harry R.Staples,

Application. July '1, 1930, Serial No. 466,126

20 Claims.

This invention has to do in a general way with well drilling equipmentand is more particularly related to devices for indicating to theoperator of such equipment at any predetermined time whether or not thehit whereby the well is being drilled, is following a vertical course.The invention is especially adaptedv for use in connection with rotarydrilling equipment. As is well known to those familiar with the art,such equipment consists in a general way of a. 'string of pipe or tubingknown as the drill stem, the lower end of which carries'a drill bit andthe upper end of which is provided with a squared section of .tubingknown as the Kelly, whereby the drill stem is rotated through the mediumof a rotary table. The upper end of the Kelly carries what is known as aswivel circulating head through which pressure fluid ordinarily known asrotary mud is delivered to the drill stem from any suitable source ofsupp It-is also well known to those familiar with the art thatconsiderable diiculty has been experienced in the practice of rotarydrilling operations in maintaing a vertical bore hole. Numerouroperators have initiated the practice of surveying the hole from time totime as it is being drilled` and the usual procedure followed in makinga survey of this nature necessitates the withdrawal of the drill stemand its associated parts and entails the use oi a special instrumentwhich must be lowered into the well by means of special apparatus, suchinstrument being designed to produce a permanent record of the directionand degree of the inclination of the well at all points throughout thelength of the survey.

It is the primary object oi' this invention to produce an indicatinginstrument which may be embodied in the drill stem and is preferablypositioned at a point adjacent the drill bit. It is not the purpose ofthe device contemplated by this invention to produce a permanent recordof the degree and direction of the inclination of the drill stem as itprogresses downwardly into the ground, but it is rather the purposeof.this invention to produce a device whereby the operator may at anypredetermined time determine whether or not the drill stem is standingvertical.

It is a further object of this invention to produce a device of theclass described wherein the indication of vertcality is evidencedthrough an increase in pressure in the circulating fluid. This object isaccomplished by providing the instrument with a valve which isassociated with gravity actuated means designed to obstruct the ow oiiluid through the device when the drill stem is vertical. The opciaticnoi the device is of course optional. so that under normal conditionswhile the drill bit is being advanced into the well, there is noobstruction in the path of the circulating iluid.

As inferred above, the preferred form of our invention embodies a devicein which the flow of circulating fluid is obstructed when the well isvertical. It is to be understood, however. that by a. comparativelysimple alteration in the arrangement of the parts embodying the devicecontemplated bythe invention, the obstruction in iluid and the increasein pressure may b e obtained when the drill stem is inclined from thevertical.

It isla further object of this invention to produce a novel type ofvalve mechanism which is perculiarly adapted for use in connection witha device of the character contemplated by this ln vention. Such valvemechanism consists in a general way of a coil spring which is interposedin the path of ilow o f the fluid so that the fluid must necessarily dowbetween the coils in the spring. The closing action of the valve isobtained simply by compressing the spring and the expansion of thespring to its normal position is, of course, elective to provide an openpassage for the ilow of circulating uid.

The device contemplated by this invention is of simple form andconstruction, it requires no additional apparatus on the derrick floor,since the usual gauge employed in indicating pump pressure on thecirculating fluid provides means for indicating the results obtained atthe bottom of the hole.

In the operation of rotary drilling equipment the iiow of fluid throughthe bit itself may at times be obstructed by the accumulation or ballingup of cuttings about the bit. and under these circumstances an increasein pressure when the device was used would not necessarily indicate thatthe well was vertical. We have, therefore, provided the devicecontemplated by this invention with means for locking the instrumentagainst operation so that when the drill stem is raised, (this being theprocedure followed to effect a closure of the valve if the well isvertical), the valve is held against closing movement. Under thesecircumstances, the circulating fluid is permitted to ow through thevalve, and if an increase in pressure is observed` it is known that suchincrease is due to some cause other than the valve mechanism and theoperator must then remove the obstruction causing the increase inpressure and again us'e the instrument without locking same to determinewhether or not the well is vertical.

The details in the construction of a preferred form of our invention.together with other objects attending its production. will be bestunderstood from he following description of the accompanying drawings,which are chosen for illustrative pui poses only. and in Which- Fig. lis a diagrammatic view illustrating in a general way a rotary welldrilling organization of the type in connection with which thisinvention is adapted for use;

Fig. 2 is a sectional elevation, partly an outside view showing thegeneral arrangement of the parts in a preferred form of devicecontemplated by this invention;

Fig. 3 is an enlarged partial sectional elevation taken in a planerepresented by the line 3-3 in Fig. 2';

Fig. 4 is a transverse section taken in a plane represented' by the line4-4 in Fig. 2;

Fig. 5 is a plan section taken in a plane represented by the line 5 -5in Fig. 3; and

Fig. 6 is a developed outside elevational view showing a preferred formof locking mechanism which is used in the device contemplated by thisinvention. E

More particularly describing the invention as herein illustrated,reference numeral 11 indicates a bore hole in which a drill stem ordrill pipe 12 is suspended. The lower end of the drill pipe 12 carriesabit, indicated by reference numeral 13, and reference numeral 14indicates the gravity actuated fluid obstructing valve contemplated bythis invention. Theupper end portion of the drill stem 12 is providedwith a Kelly 15 which extends through a Kelly bushing provided in arotary table 16. The upper end of the Kelly carries a swivel head 17into which circulating fluid is delivered through abuse-18 from a fluidYcirculating pump 19. The pump 19 is connected to the hose 18, through astand pipe 20 and the pumping system is provided with a pressure gaugeindicated by reference numeral 2l.

The details in the construction of the device contemplated by thisinvention are best illustrated in Figs. 2. to 6, inclusive, where thedevice is shown as comprising a telescoping body 14, such body includingan inner tubular element or part 25 and an outer tubular part 26. Theseparts are so shaped and so arranged with respect to each other as toform an irmer chamber 27 and an outer chamber 28. The upper end portionof the outer tube 26 is attached to a sleeve or cylinder member 29 andthe upper end portion of the inner tube 25 contains a bushing 30 whichis attached to a connecting tube 31, such connecting tube having itsupper end portion secured in the lower end of a tubular core member 33.'I'he core member 33 extends upwardly through a packing gland 34provided in the top of the sleeve or cylinder member 29 and has itsupper end secured to a sub 35 which in turn is attached to a section ofthe drill stem- 12. The lower end portion of the outer tube or barrel 26receives a sub 36 which may be attached to another section of the drillstem 12 or may be secured directly t the bit .13.

The circulating fluid coming from the drill pipe is delivered downwardlythrough the tubular core 33 into the connecting tube 3l, from which itpasses through apertures 38 into the outer chamber 28. The iiuid fromthe outer chamber 28 is delivered into the lower endv portion of theinner chamber 27 through a series of apertures 39 which are provided inthe lower end of the inner tube 25.

Reference numeral 40 indicates a tubular plunger which is secured to thelower end portion of the inner tube 25 and is in iiuid tight slidingengagement with the interior of the barrel 26. Reference numeral 41indicates a coil spring which rests upon the upper inner end portion ofthe plunger 40 in the lower end of the inner tube 25. This coil spring41 is associated with a spring control plunger 42 and in combinationwith the spring control plunger constitutes a valve mechanism which isemployed for the purpose of obstructing the -ilow of fluid from theouter chamber 28 into the lower end portion of the inner chamber 27. Itwill be observed that so long as the spring 4l is in its normal expandedposition the circulating fluid flows freely between the coils of thespring into the lower end portion of the inner chamber and downwardlythrough the tubular plunger 40 into the lower end of the drill string orinto the bit as the case may be. either by moving the plunger 42downwardly toward the plunger 40, or by holding the plunger 42stationary and raising the plunger 40 upwardly, such compression iseffective to close the spaces between the coils of the spring, therebyobstruct- When the coil spring is compressed ing the ow of fluid throughthe drill pipe, such obstruction of ow being eective to increase theiluid pressure in the drill pipe which is evidenced upon the gauge 2l,thereby indicating to the operator that the well is either vertical orinclined from the vertical, depending upon the mechanism which isemployed to bring about the compression of the spring.

As pointed out above, this form of our invention is designed to effectan obstruction of flow and a consequent increase in head pressure whenthe instrument or the barrel 26 is vertical. The mechanism for effectingsuchindication is, as inferred above, actuated by gravity and consistsof a pendulum which is arranged so as to hold the spring control plunger42 against upward movement with the plunger 40 and the inner tube 25when the barrel is in a vertical position. This pendulum is indicated byreference numeral 45 and is shown as hav-- ing provided in its upper enda slot or notch 46 through which a transverse pin 47 extends. The pin 47is recessed in its mid portion as indicated at 49 in Fig. 5 and providesa bearing which rests upon the lower surface of an eye 50 suspended bymeans of a stem 51 from a head member 52. The head member 52 has asliding t in the inner tube 25 and is held against movement relative tothe barrel 26 by means of a transverse pin 53. The tube 25 is providedwith a pair of aligned slots 54 which are positioned so as to permitmovement of the tube 25 re1- ative to the pin 53.

The pendulum 45 is enclosed within a pendulum housing 55 which issecured at its upper end to the head member 52 and has an aperturedbottom plug 56 provided in its lower end portion. Reference numeral 57indicates what will hereinafter be referred to as a valve control stemwhich is mounted on the valve control plunger 42 and extends upwardlythrough a packing gland 58 provided in the bottom plug 56 into thependulum housing 55 where its upper end portion is provided with atapered head 59 situated in alignment with a tapered recess 60 formed inthe bottom of the pendulum when the pendulum is hanging vertical.

With regard to the means for suspending the pendulum 45, it will benoted that the pin and eye construction indicated at 47 and 50respectively, forms a single point contact from` which the pendulum issuspended, and it will also be observed that the notch 46 is ofsuiiicient width to permit the pendulums swinging through an arc in anydirection which is great enough to permit the clearance of the pin 59and the lower end of the pendulum 45 when the body 26 is inclined at apredetermined angle from the vertical. This angle is, of course,dependent upon the length of the pendulum and its relation with 'respectto the engagement member 59. In the preferred form of our invention wehave constructed a device so that the pendulum will clear the engagementmember 59 when the barrel is inclined one degree from the vertical.

It will be noted that in their normal positions the lower end of thependulum and the upper end of the engagement member are spaced asubstantial distance apart so as to permitthe locking action referred tohereinabove, the operation of. which will be hereinafter more specicallypointed out.

Reference numerals 65 and 66 indicate guide plates which are containedwithin the pendulum housing 55 and are yieldably held in spaced relationwith each other by means of a coil spring 67', such spring being adaptedto maintain the valve control plunger 42 in 'its normal position whenthe device is not in use.

As pointed out above, the device contemplated by this invention isadapted to be interposed in a drill string and to remain therein duringthe drilling operation. Since the body 14 is of a telescoplng nature, itis necessary that it be provided with means for transmitting torque fromthe inner section thereof to its outer section. Such means are shown ascomprising splines 67 which are formed on opposite sides of the lowerend portion of the tubular core 33. These splines are adapted to engageshoulders 68 which are provided on the interior of the sleeve orcylinder section 29. The shoulders 68 may be formed by milling theinterior 'of the section 29 to the proper shape, or they may be providedby means of segmental cylindrical plates which are welded or otherwiserigidly attached to the interior of the sleeve section 29, as indicatedin Fig. 4. This latter form of construction is preferable in the deviceas shown and described above in that it makes possible a convenientmanner of forming a lock for optionally holding the telcscoping partsagainst expansion to a point at which the engagement member 59 will bebrought into contact with the lower end of the pendulum 60.- This lockis a modification of the Well known bayonet joint and consists merely ofa pair of offset recesses indicated in the development in Fig. 6 byreference numerals 69 and 70. It will be noted that the upper endportions of the lugs or splines 67 are rounded and that the upper endportions of the recesses 69 and 70 are likewise rounded so that when thedevice is locked, which is effected by rotating the drill stem clockwiseand then raising the same, it is impossible to disengage the bayonetjoint. It will also be seen that the recess '70 is considerably longerthan the spline 67 which permits relative longitudinal movement betweenthe parts to test for verticality of the hole.

The procedure followed in taking a reading is to rotate the drill stemclock-Wise a sufficient distance to bring the lsplines 6'7 intoengagement with the shoulders '71. An upward force is then applied tothe drill stem, such force being effective to raise the inner tube bymeans of the tubular core 33 together with its associated parts,including the spring valve 41 and the spring control plunger 42, untilthe engagement member 59 occupies the dot and dash line positionindicated by reference numeral 59a in Fig. 3. If the barrel 26 isvertical and the pendulum 45 and the engagement member 59 are inalignment,

this last mentioned movement will bring the engagement member 59 intocontact'with the recess 60 in the lower end of the pendulum and thecontinued upward movement of the drill stem Will force the plungerupwardly toward the spring -control plunger 42 which is being heldstationary, such movement being effective to cornpress the spring'41,thereby obstructing the flow of iiuid from the outer chamber -28 intothe inner chamber 27 and consequently effecting an increase in pressurein the circulating iiuid which is indicated on the gauge 21. If the wellis inclined from the vertical one degree or more, the upward movement ofthe plunger 40-and its associated parts in the manner described abovewill continue beyond the position 59a, permitting the engagement member59 to pass by the lower end of the pendulum 45, thus preventing theccmpression of the spring 41 and the consequent obstruction of flow.fore, that if no increase in pressure is observed when the drill stem israised in the manner described above, the operator knows that the wellis inclined from the vertical and may take the necessary precautions,well known to those familiar with the art, to straighten the same. If anincrease in pressure has been observed, which in generalpractice resultsin shutting off the flow, and the operator wishes to check this readingto determine whether such increase in pressure is due to an obstructionin the bit or is due to the compression of the spring 41, it is merelynecessary to lower the bit onto the bottom of the hole, rotate the samecounter-clockwise until the splines occupy the position vshown It willbe apparent, therein Fig. 6 and again apply an upward force to the drillstem. It will be observed that the recess 69 is shorter than the recess'70 and that as a result the spline 67 moves upwardly a less distancethan in the former operation. The spring 41 is slightly compressed inthis operation, but not suflciently to materiallybbstruct the flow offluid. If, after such operation, no material increase in pressure isobserved, the operator knows that there is a clear passage through thedrill stem and the bit and this demonstrates conclusively that hisprevious reading indicates the well to be vertical. If a large increasein pres- Sure is observed in this last described operation, the operatorknows that the former increase in pressure may have been dueY either tothe obstruction of flow caused by the spring 41 or that it may be due tosome other obstruction in the drill bit or the drill pipe and he musttake the necessary measures to determine whether or not the passage. inthe bit or the passage through the drill pipe is obstructed.

It will be apparent from the foregoing description that the devicecontemplated by this invention is of simple form and construction, thatit does not require expert attention, nor does it entail the use ofadditional equipment on the derrick floor; there is no part subjected toexcessive wear by the abrasive action of the crculating fluid; thependulum is entirely enclosed and is protected from the action of thecirculating fluid and the instrument may be used at any time during thedrilling operation to indicate whether or not the well is following avertical course.

It is to be understood that while we have herein described andillustrated one preferred form of our invention, the invention is notlimited to the precise construction set forth above, but in.-

cludes within its scope whatever changes fairly come within the spiritof the appended claims.

I claim as my invention:

1. In combination with a drill pipe and a n uid pressure system forforcing drilling fluid through said drill pipe: means for indicatingwhether or not said pipe is vertical by a pressure change in said uidembodying: a'telescoping body member in said pipe; a valve in said bodymember yadapted to be opened and/closed' by the telescoping actionthereof; and gravity actuated means in said body for controlling saidvalve.

2. In combination with a drill pipe and a fluid pressure system forforcing drilling iluid through said drill pipe: means for indicatingwhether or not said pipe is vertical by a pressure change in said /iiuidembodying: a telescoping body member in said pipe; a valve in said bodymember adapted to be opened and closed by the telescoping actionthereof; gravity actuated means in said body for controlling said valve;and locking means for optionally holding said body against expansion.

3. In\eombination with a drill pipe and a fluid pressure system forforcing drilling fluid through said drill pipe; means for indicatingwhether or not said pipe is vertical by a pressure change in said fluidembodying: a telescoping body member in said pipe; a valve 4in said bodymember `adapted to be opened and closed by the telescoping actionthereof; and gravity actuated means in said body dependent upon theverticality of said body for controlling said valve.

4. For use in combination with a drill pipe and a iluid pressure system,a device for indicating whether or not said pipe is vertical by pressurechange in said iiuid pressure system embodying:

a tubular body; a tubular plunger in said body; ,f

a tubular plunger rod having its lower end portion attached to saidplunger and having its upper end portion connected to saiddrill pipe,

- said rod beingshaped so as to form an outer chamber and an innerchamber in said body; means for delivering pressure iluidfrom ysaiddrill pipe into said outer chamber; valve means foracontrollablydelivering pressure iiuid from said outer chamber into said plunger; andgravity actuated means dependent upon the verti-y cality of said'bodyfor controlling-said valve.

5. For use in combinationwith a drill pipe and a fluid pressure system,a,device for indicating whether or not said pipe is vertical by pressurechange in saidl fluid pressure system embodying: a tubular body; atubular plunger in said body; a tubular plunger r od having its lowerend portion attached to said plunger 'and having its upper end portionconnected to said drill pipe, said rod being shaped so as to form anouter chamber and an inner chamber in said body with apertures in saidrod connecting said chambers; means for delivering pressure iiuid fromsaid drill pipe into said outer chamber; valve means for controllablydelivering pressure fluid from said outer chamber into said plunger; andgravity actuated means dependent upon the verticality of said body forcontrolling said valve, said valve comprising a coil spring associatedwith said apertures in said tubular plunger rod.

6. For use in combination with a drill pipe and a fluid pressure system,a device for indilower end portion attached to said plunger and` havingits upper end portion connected to said drill pipe, said rod beingshaped so as to form j an outer chamber and an inner chamber in saidbody with apertures in said rod connecting said chambers; means fordelivering pressure fluid from said drill pipe into said outer chamber;

valvelmeans for controllably delivering pressure uid from said outerchamber into said plunger, said valve comprising a coil springassociated with said apertures in said tubular plunger rod,

a valve control plunger for compressing said springr` duringlongitudinal movement of said tu- L bodying: a tubular body; a tubularplunger inV said body; a tubular plunger rod having its lower endportion attached to said plunger and having its upper end portionconnected to said drill pipe, said rod being shaped so as to form anouter chamber and an inner chamber in said body with apertures in saidrod connecting said chambers;

-means for delivering pressure uid' from said drill pipe into said'outerchamber; valve means for controllably delivering pressure fluid fromsaid outer chamber into said plunger, said valve comprising a coilspring associated with .said apertures in said tubular plunger rod, avalve control plunger for compressing said spring during longitudinalmovement of said plunger/in said body; a stem on said valve controlplunger; and gravity actuated means dependent upon the verticality ofsaid body and adapted to engage said stem for governing the movement ofsaid valve control plunger. I

K 8. For use in cdmbinat'ion Vwith a drill pipe and a iiuid pressuresystem; a device for indi' eating whether or not said pipe,is verticalby pressure change'in said fluid' pressure system embodying: a tubularbody; a tubular plunger in said body; a tubular plunger rod having itslower end portion attached to said plunger and having its upper endportion connected to said drill pipe, said rod being shaped so as toform an outer chamber and an inner chamber in said body with aperturesin saidv rod connecting said chambers; means for delivering pressurefluid from said drill pipe into said outer chamber; valve means forcontrollably delivering .pressure fluid from said outer chamber intosaid plunger, said valve comprising a coil spring associated with saidapertures in said tubular plunger rod, a valve control plunger forcompressing said Aspring during longitudinal movement of said plunger insaid body, a stem on said valve control plunger; and a pendulumsuspended in said body and adapted to engage said stem when said body isvertical for compressing said spring, lthereby closing said valve duringan upward movement of said plunger in said body.

9. A device adapted for interposition in a pressure line for obstructingthe flow of fluid therethrough when said line is vertical embodying: abody composed' of relatively movable telescoping parts forming an innerand an outer chamber; means for delivering fluid into the outer chamber;valve means for controllably ladmitting fluid from the outer chamberinto the inner chamber; and gravity actuated means for governing theoperation of said valve.

1G. A device adapted for interposition in a pressure line forobstructing the flow of uid therethrough when said line is verticalembodying: a body composed of relatively movable telescoping partsforming an inner and an outer chamber; means for delivering uid into theouter chamber; valve means for controllably admitting fluid from theouter chamber into the inner chamber; and gravity actuated means forclosing said valve during relative longitudinal movement of saidtelescoping parts when said body is vertical.

11. A device adapted for interposition in a pressure line forobstructing the flow of fluid therethrough when said line is verticalembodying: a body composed of relatively movable telescoping partsforming an inner and an outer chamber;

means for delivering fluid into the outer chamber; valve means forcontrollably admitting fluid from the outer chamber into the innerchamber; and gravity actuated means for closing said valve duringrelative longitudinal movement of said telescoping parts when said bodyis vertical, said gravity actuated means being arranged so that saidvalve remains open if the -body is inclined from the vertical.

12. A device adapted for interposition in a pressure line forobstructing the flow of fluid therethrough when said line is verticalembodying; a` body composed of relatively movable telescoping partsforming an inner and an outer chamber with apertures in the innertelescoping part connectingsaid chambers; means for delivering uid intothe outer chamber; valve means for controllably admitting uid from theouter chamber into the inner chamber, said valve comprising a coilspring associated with said apertures; and gravity actuated means forgoverning the operation of said valve.

13. A device adapted for interposition in a pressure line forobstructing the flow of fluid therethrough when said line is verticalembodying: a body composed of relatively movable telescoping partsforming an inner andan outer chamber with apertures in the innertelescoping part connecting said chambers; means for delivering fluidinto the outer chamber; valve means for controllably admitting fluidfrom the outer chamber into the inner chamber, said valve comprising acoil. spring associated with said apertures, a spring control plunger insaid inner telescoping part, an upwardly projecting stem on said controlplunger; and gravity actuated means arranged so as to engage said stemand compress said spring during a relative longitudinal movement of saidtelescoping parts when said body is vertical.

14. A device adapted for interposition in a pressure line forobstructing the flow of fluid therethrough when said line is verticalembodying: a body composed of relatively movable telescoping partsforming an inner and an outer chamber with apertures in the innertelescoping part connecting said chambers; means for delivering fluidinto the outer chamber; valve means for controllably admitting fluidfrom the outer chamber into the inner chamber'. said valve comprising acoil spring associated with said apertures, a spring control plunger insaid inner telescoping part, an upwardly projecting stem on said controlplunger; and a pendulum suspended in said body so as to engage said stemand compress said spring during relative longitudinal movement oftelescoping parts when said body is vertical.

15. A device adapted for interposition in a pressure line forobstructing the flow of fluid therethrough when said line is verticalembodying: a body composed of relatively movable telescoping partsforming an inner and an outer chamber; means for delivering fluid intothe outer chamber; valve means for controllably admitting fluid from theouter chamber into the inner chamber; and gravity actuated meansdependent upon relative longitudinal movement of said telescoping partsfor governing the operation of said valve.

16. A device adapted for interposition in a pressure line forobstructing the flow of fluid therethrough when said line is verticalembodying: a body composed of relatively movable telescoping partsforming an inner and an outer chamber; means for delivering fluid intothe outer chamber; valve means for controllably admitting fluid from theouter chamber into the inner chamber; gravity actuated means dependentupon relative longitudinal movement of saidltelescoping parts forgoverning the operation of said valve; and means for optionally lockingsaid telescoping parts so as to permit the operation of said valve whenan expanding force is applied to said telescoping body.

17. For use in combination with a drill pipe and a fluid circulatingsystem, means for obstructing the flow of fluid therethrough when saidpipe is vertical embodying: a body comprising two telescoping tubesarranged so as to form an inner chamber and an outer chamber; means forattaching the upper end of the inner tube to a section of said drillpipe; means for attaching the lower end of the outer tube to a. sectionof said drill pipe; means for delivering circulating fluid from saiddrill pipe to said outer chamber,

said inner tube being provided-With apertures to admit fluid from saidouter chamber into said inner chamber; a coil spring and plungerorganization in said inner tube arranged so as to obstruct the flow offluid into said inner chamber when said spring is compressed; andgravity controlled means for compressing said spring during relativelongitudinal movement of said telescoping parts when said pipe isvertical.

18. For use in combination with a pressure line, means for optionallyobstructing the flow of fluid therethrough when said line is vertical,embodying: a coil spring positioned in the path of flow and arranged sothat the uid must flow between the coils of said spring; and gravitycontrolled means for compressing said spring when said pipe is vertical.

19. For use in combination with a pressure line, means for obstructingthe flow of fluid therethrough to indicate the verticality of said lineembodying: a coil spring positioned in the path of Vflow so that thefluid must flow between the coils thereof; means for compressing saidspring; and gravity actuated means for controlling said springcompressing means.

20. For use in combination with a pressure line, means for obstructingthe flow of fluid therethrough to indicate the verticality of said lineembodying: a coil spring positioned in the path of flow so that thefluid must flow between the coils thereof; means comprising relativelymovable parts for compressing said spring; and gravity actuated meansfor controlling said spring compressing means.

TI-IEODORE L. LYNCH. HARRY L. RILLING. HOWARD A. REDFIELD.

CERTIFICATE OF CORRECTION.

Patent No. 1,988,741. January 22. 1935.-

THEODORE L, LYNCH, HARRY L. RlLLlNG, and HOWARD A. REDFIELD.

lt is hereby certified that the above numbered patent was erroneouslyissued to "Harry R. Staples, of Los Angeles, California," as assignee ofthe entire interest in said invention whereas said patent should havebeen issued`to Theodore L. Lynch, HarryL. Rilling and Harry R. Staples,of Los Angeles, California, said Staples being assignee of the entireundivided interest of said HowardA. Redfield, as shown by the records ofassignments in nthis office; and that the said Letters Patent should beread with this correction therein that the same may conform to therecord of the case in the Patent Office.

Signed and sealed this 19th day of March, A D. 1935.

Leslie Frazer (Seal) Acting Commissioner of Patents.

